Electric switch



' Aug. 18, 1931.

J. E. BANCROFT- 1,819,061

ELECTRIC SWITCH Filed Oct. 12. 1928 INVENTOR L JAMES E. BqNcRoPr W l T Nv E S S BY v a. a I Y @mW Patented Aug. 18, i931 UNITED STAT S PATENT OFFICE JAMES E. BANCROFT, 01' DE'EBOIT. IOHIGAN, ASSIGHOB '10 DOOR-Hm CORPORA- T1011, 01 WORCESTER, IASSAGHVBETTS, A CORPORATION OF IASSAOHUBEITB ELIGTRIC SWITCH Application and October :2; 1928. Serial No. 312,095.

This invention relates to control devices, and more particularly to electro-magnetically operated electric switches.

Switches of this type are frequently an- 5 ran ed in pairs for various purposes, such as t e operation of a reversing electric motor, one switch being used to operate the motor in a forward direction and the other in a reverse direction. Mechanism is usually provided to 19 interlock the switches and thereby'eliminate any possibility of one switch being closed be ore the other is opened. The operation of the switches is ordinarily controlled by means of push buttons, and it has heretofore as been customary to utihze three push buttons for each pair of switches, one to start the motor in a forward direction, one to etc the motor, and one to start it in a reverse. rection. I v I ac It is one object of my invention to provide a construction whereb two push buttons will ive complete control over a air ofinterocked switches, permitting sit or switch to be opened or closed at will.

It is a further object of my invention to provide a simply constructexl and inexpensive interlocking mechanism for a pair of electro-magneticall operated switches,

It is a further ject to provide an; interlockin mechanism which will form part of the ho ding circuit of a closed switch and maintain the switch in a closed position after the release of the corresponding push butf tons.

It is a further object to provide an interlocking mechanism whichwill automatically open a closed switch whenever an attempt is made to close the other switch.

With these and other ob'e'cts in view, as

60 except when the other is open. Theinterposition. i for its Fig. 1;

ig. 3 is a cross section on the line 8--3 of F g. 1 certain parts being omitted for clearness 0 illustration;

Fi 4 is a view similar to Fig. 3, except that th switches are open;

Fig. 5 is a view similar to Fig. 3, showing the position of the parts immediately after an attempt is made to close theopen switch;

Fig. 6 1s a wiring diagram of the holding circuitsd n '1' is a wiring diagram of the main switc circuits.

-The embodiment illustrated comprises a vertical rectangular sup rtin panel 10, preferably constructed 0 insufatmg material. On opposite sides of the panel and near the'lower portion thereof, I mount a pair of brackets 11 and 12 arranged to en port the switch members 14: and 15, whic are preferably ivota-lly attached to the brackets y means o horizontal pins 17 and 18. These parts are so'shaped and arranged that the upper portions of the switch members tend to fall 'outwardl away from the panel under the influence o gravity, and this outward pivotal movement is limited by downwardl extending projections 20 and 21 on the switc members, which strike against lugs 23 and '24 formed on the brackets. With this construction each switch is biased to the open The switch members 14 and 15 are arranged to carry sets of contacts 26 and 27 respectively. Though I have shown three of these contacts in each group, the particular number is immaterial so far as the present invention I is concerned, but depends entirely upon the use to which the device is to be put. In order to provide a suitable support for the contacts, each switch member carries near its upper extremity a horizontal rectangular bar 29 of insulating material, on which are mounted downwardly extending arms 30. The contacts 26 and 27 are pivoted at their lower extremities to the lower portions of the arms 30 and are normally held against the upper ends of the arms by small compression springs 82 which bear against the enlarged heads of rivets 33 attached to the arms 30. The pivotal connection between the contacts 26 and 27 and the arms 30 may be formed in any suitable manner. As shown, the contacts have reduced ends projecting into openings 31 in the arms 30.

Cooperating with the contacts 26 and 27 is a set of three contacts 35 which preferably extend entirely through the upper portion of the panel and are provided with enlarged heads 36 at their ends. These parts are so shaped and located that when the switch members are swung inwardly the contacts will touch, and the springs 32 will insure an even bearing pressure.

As an illustration of one use to which the device may be put, I have shown the main switches connected in Fig. 7 to operate a motor 38 of the three phase induction type. The three phase power supply 39 is connected to the stationary contacts 35, and the motor is connected to the movable contacts 26 and 27, two of the connections being crossed as shown, in a manner well known in this art, in order to provide for running the motor in either direction.

In order to close the main switches when desired, I provide each switch member with an armature 41 of magnetic material, these armatures being mounted on the inward side of the switch member toward the central panel. On opposite sides of the panel I mount a pair of solenoids or electro-magnets 43 and 44, which are so located that when energized they will attract the corresponding armature and thus pull the corresponding switch member inwardly. The solenoid conneetions may be wired as shown diagrammatically in Fig. 6. Solenoid 43 is connected by a wire 46 to one side of a series of push buttons or control switches 47, and by a wire 49 to one side of a power supply 50, which may consist of a battery or generator, or any other suitable source of electric energy. Solenoid 44 is connected to the wire 49 and b means of a wire '51 to one side of another series of push buttons 52. Both sets of push buttons are connected by a wire 53 to the other side of the power supply 50. There may be any number of push buttons, located at places convenient for the operator.

It will be noted that with the device as so far described, ifone push button 52 is actuated and one push button 47 is then actuated before the other is released, both solenoids will be energized at the same time, which will cause the closing of both main switches and a short circuit of the main power supply 39. Moreover, in order to maintain energization of either solenoid and thus hold the switch closed, it is necessary to hold the proper push button closed. This is, of course, inconvenient.

In order to overcome these difficulties, I provide an interlocking device which in the present embodiment comprises an interlocking member or bar 60. This bar extends through an opening in the panel 10 in a direction substantially perpendicular thereto, and

is mounted for pivotal movement on a hori-' zontal pin 61 attached to a bracket 63, which is fastened to the panel. The bar 60 is yieldingly held in a horizontal position symmetrical with respect to both switch members by a small coiled spring 64 surrounding the pin 61 and arranged with one end fastened to the bracket 63 and the other end attached to the interlocking bar.

For cooperation with the interlocking bar I provide a pair of interlocking fingers 66 and 67, one on each of the insulating bars 29. Each finger is made of conducting material, and is preferably bent inwardly and downwardly at its upper extremity 68 as shown, in order to more effectively co-act with the bar 60. For this same purpose, the bar 60 is preferably formed with bluntly pointed wedge shaped ends so arranged as form cam surfaces adapted to contact on their tapered sides with the tops of the downwardly bent ends 68 of the bar 60.

As shown in Fig. 6, the bar 60 is connected by a wire 69 to wire 53; finger 66 is connected to wire 46; and finger 67 is connected to wire 51. The parts are so arranged that when either main switch is closed, the corresponding interlocking finger will strike against the interlockingbar60,thus closing an independent circuit across the push button used to close the main switch. This push button can then be released without de-energizing the solenoid and opening the switch.

I Moreover, as one switch is moved to its closed position, the interlocking finger tips up the interlocking bar owing to the wedge shapes of the contacting parts, thus lowering the other end of the bar into the path of the other finger, and prevents closing of the other main switch. Suitable insulation is Y provided to prevent electrical contact of the inter-locking bar 60 with the fingers 66 or 67 of the open switch, when the bar is thus tipped. As illustrated, this insulation ma be accomplished by mounting a small block or cam member 70 on each finger and insulating it therefroma Each block 70 has its upper side shaped to lie in the plane of the beveled top edge of the part 68 so that the lower beveled edge of the bar so may ride over the block 76- when moving to the position shown at the right hand end of Fig. 3. lfiach block 7 0 has a cam surface 72 so shaped'gihat if an attempt is made to close the other main switch, the cam surface 72 will strike the upper side 73 of the beveled end of the bar 60 (Fig. 3) and force it down still more, as shown in Fig. 5, thereby break the connection between the bar and the 0 er finger and de-energizing the other solenoid. The

interlocking bar 1s prevented from tipping too far by providing'the block 70 with a notch 74, as shown in Figs. 3 and 5, which fits the end of the bar 60 and prevents further downward movement of that end.

The operation of my invention will now be apparent from the above disclosure. With the parts in the position shown in Fig. 4, both main switches are open, and the motor 38 is at rest. If now one of the push buttons 52 is closed momentarily, a circuit is established through wire 53, wire 51, solenoid 44, and wire 49. Solenoid 44 is therefore energized, and will attract armature 41 on switch member 15. The switch arm will swing upwardly and inwardly about pin 18, and contacts 27 will strike against contacts 35, thus connecting motor 38 to power supply 39 and starting the motor in a forward direction.

As the main switch closes, finger 67 strikes the underside of the bar 60, thus tipping it upwardly against the action of spring 64, as shown in Fig. 3, andshort-circuiting ush button 52 through wire 69. This, there ore, maintains energization of solenoid"44, and push button 52 can be released without cansin the main switch to o n case it is now desir to stop motor, it is merely necessary to press one of the push buttons 47 momentarily. This closes a circuit through wire 53, wire 46, solenoid 43, and wire 49, energizing solenoid 43 and attracting armature 41 on switch member 14. This switch member swin s in until cam block 70 strikes the top 73 of the bar and swings that end downwardly, as shown in Fig. 5, the movement being insufiicient to effect closure between contacts 26 and 35, but sufli'cient to lift the opposite end of bar 60 and break its contact with finger 67. This de-energizes solenoid 44, and switch member 15 falls out, stopping the motor. Since block is insulated, its contact with the interlocking bar does'flnot maintain energization of solenoid 43, and switch member 14 will drop back upon release of push button 47, whereu n the arts resume their original positipns ,ownin ig. 4. To operate the motor in the opposite direction it is now merely necessary to press one of the buttons 47 again. Since the two sides of the device are symmetrical, the resulting efiects will be clear from the above description.

After the motor has been started in a given direction by one of the push buttons, it may be stopped by pressing the opposite push button, and it may be started in the reverse direction by pressing this same button a second time. The interlocking mechanism is simple and inex nsive, an effectively prevents closure oi one main switch before 0 ning the other. The omission of the thir ush button heretofore used to open the switc simplifies the wiring and installation. It will be apparent from the above disclosure that the solenoids may be arranged to efiect o ning of the switches as well as for closing t em, and the claims presented herewith are to be 'ven such an interpretation as will cover eitihr arrangement.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is 1. A control device comprising an electric switch, a solenoid arranged to throw the switch in one direction when energized, a second electric switch, a second solenoid arranged to throw the second switch in one direction when energized, an interlocking device including a member normally in an open circuit with said solenoids which is arranged to permit the o eration of either switch alone and prevent t e simultaneous operation of both switches, and means forming an electrical connection, tially thrown by its solenoid, between said member and the solenoid corresponding to the switch being thrown to maintain energwation of said solenoid and hold the switch in the new position.

2. A control device comprising an electric switch, a solenoid arranged to actuate the when either switch is iniposition, a second solenoid arran d to c ose the second switch when energize a mechanism arranged to prevent the closin of either switch when the other switch is c osed, and means forming an electrical connection, when either of said switches is closed by the co pletion' of a circuit through the correspofiing solenoid and its resu ting enorglzatio which completes. an independent circui through the corresponding solenoid an thereby maintains .energization of the solenoid after the o ning of the first circuit.

4. A control evice comprising an electric switch biased to a given position, a solenoid arranged to move the switch when energized, a second electric switch biased to a given position, a second solenoid arranged to move the second switch when energized, and means effective, after one solenoid has been energized, to de-energize this solenoid upon energization of the other solenoid.

5. A control device comprising an electric switch, a solenoid arranged to actuate the switch when energized, a second electric switch, a second solenoid arranged to actuate the second switch when energized, means forming an electrical connection, when either of said switches is actuated by the completion of a circuit through the corresponding solenoid and its resulting energization, which completes an independent circuit through the corresponding solenoid and thereby maintains energization of the solenoid after the opening of the first circuit, and means efiective to open this independent circu1t and deenergize the solenoid upon energization of the other solenoid.

6. A control device comprising two switches having members biased to open position, a solenoid arranged to close each switch independently of the other when energized by the completion of a. circuit therethrough, means effective, when a switch is closed, to maintain energization of the corresponding solenoid by the completion of an independent circuit therethrough, thereby holding the switch closed after the first circuit has been opened, and means to open the independent circuit and thereby de-energize the solenoid corresponding to the closed switch when the other solenoid is energized, thus causing the closed switch to open.

7. A control device comprising an electric switch, a solenoid arranged to close the switch when energized, a second electric switch, a second solenoid arranged to close the second switch when energized, an interlocking member arranged to prevent the simultaneous closing otboth switches, means to connect the interlocking member in series with a solenoid when the corresponding switch is closed by the completion of a circuit through the solenoid, and thereby complete an independent circuit which serves to maintain energization of the solenoid after opening of the first circuit, and means to break the con nection with the interlocking member upon energization of the other solenoid.

8. A control device comprising a pair of electric'switch members biased to a given position, a solenoid for each switch member arranged to move the switch member when energized, a contact member movable with each switch, and a movable interlocking mechanism arranged to make electrical contact with either contact member when the corresponding switch is operated and complete a circuit through the solenoid and thereby maintain it energized, said mechanism and contact member being so constructed that when one switch member is moved the mechanism is moved to a position which prevents operation of the other switch.

9. A control device comprising a pair of electric switches having movable members biased to an open position, a solenoid for each switch arranged to move its switch member to a closed position when energized, a movable interlocking bar, a contact member movable with each switch member arranged to contact with said bar, when one of the switches is closed, and complete an electric circuit through the corresponding solenoid and to simultaneously move the bar to a second position, and insulation so located and arranged as to' prevent electric contact of the bar in such second position with the other contact member when an attempt is made to close the other switch. 7

10. A control device comprising a pair of electric switches having movable members biased to an open position, a solenoid for each switch arranged to move its switch member to a closed position when energized, a plvotally mounted interlocking bar normally located in an inoperative position, a finger movable with each switch member to engage said bar and move it to a second position, said bar and the finger engaged thereby serving to close a circuit to the corresponding solenoid and hold the switch closed, the other finger being arranged to move the bar to a third position and out of electrical contact with th engaged finger when an attempt is made to close the other main switch, and insulation between said other finger and the bar to prevent electrical contact therebetween while the bar is being so moved from said second positlon.

11. A control device comprising two opposed pivotally mounted switch members biased to an open position, solenoids connected to close the switches, fingers movable with the switch members, and an interlocking bar pivotally mounted sothat one end may make electrical contact with one of said fingers when the corresponding switch is closed and its other end will move into the path of the other finger and prevent both switches from being closed simultaneously, said finger and bar when in contact forming an electric circuit through the corresponding solenoid to maintain the same energized.

12. A control device comprising two main switches having opposed pivotally mounted switch members biased to an open position, two solenoids connected to close said switch members, fingers mounted to move with the switch members, a bar pivotally mounted between the switch members and arranged so that its ends may electrically contact with either one of said fingers and make a circuit through the solenoid which actuates the corresponding switch, said bar havinglcam surfaces at its posite ends en 1 e by said fingers whic are so sha when one switch is closed the corresponding finger moves the bar to a position which interferes with free movement of the other finger and its switch, and insulation a l a to prevent electrical contact between opposite finger and the bar.

13. A control device comprising a pair of electric switch members p1votally mounted onapanel and biased to an open position, a solenoid for each switch member when ener zed to close the switch corres onding t ereto, an interloc bar pivota 1y mounted on the panel tween the switch members, means to hold the bar yieldingly in a positlon symmetrical with respect to both switch members, a contact on each :0 switch member arranged to strike the bar when the switch is closed and deflect it from its normal position while at the same time completing a circuit through the solenoid correspon ing to the closed switch, and an insulated member on each switch member which is so shaped as to strike the interlocking bar if an attempt is made to close a switch while the other is closed and deflect the bar even more from its normal position, thereby breaking the circuit through the solenoid correspondm to the closed switch and causing this switch to open.

'14. A control device comprising two switches having opposed pivotally mounted as switch members biased to an open ition, two solenoids connected to close sai switch members, fingers mounted to move with the switch members, a bar pivotallymounted so that its ends may contact succemively with 40 the fingers, cam surfaces on the to and the bottom of each end of the bar, sai rts bein so arranged that closing a switc causes a finger to make electrical contact with the I under cam surface on one end of the bar and a rock the other end into the path of movement of the other finger, insulation so located as to prevent electrical contact between said other end and the other finger, electrical connections between the bar and the contacti 5 finger through the solenoid of the switc which has been closed, and a cam surface on each finger engageable with the top cam surface of the bar and arranged to move the bar, if an attem t is made to close a switch while the other 13 closed, and thereby break the electrical contact between the bar and the first engaged finger and so release the closed switch member.

Signed at Detroit, Michigan, this 8th day so of October, 1928.

JAMES E. BANCROFT. 

